Seal for a controllable coolant pump

ABSTRACT

A controllable coolant pump which has a pump housing. In the pump housing a pump shaft is arranged, which connects a drive wheel to an impeller wheel. In the operating state of the coolant pump, during a rotation of the impeller wheel, coolant is sucked in via a cover disk which is mounted in front of a suction space, and is conveyed into an annular channel of the pump housing. A delivery volume of the coolant pump can be influenced via an actuator which interacts with an axially displaceable guide plate assigned to the impeller wheel. An elastic sealing element is provided for effective sealing of an annular gap which is produced in a functionally required manner between the impeller wheel and the guide plate. The sealing element is inserted in an annular groove of the impeller wheel and is supported sealingly on a cylindrical section of the guide plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of DE 10 2010 046 450.3 filed Sep. 24, 2010, which is incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a controllable coolant pump which is preferably intended for the cooling circuit of an internal combustion engine.

BACKGROUND OF THE INVENTION

Coolant pumps of this type are preferably used, in order to shorten the cold running phase in internal combustion engines. After a start of a cooled internal combustion engine, it is advantageous if first of all forced circulation of the coolant is suppressed, in order for it to be possible for the operating temperature to be reached more rapidly. This measure reduces friction losses and at the same time improves the emissions values of the internal combustion engine in this operating phase. In order to influence the delivery volume of coolant pumps, it is known to vary the drive speed of the impeller wheels or to use a control or regulating valve in the coolant circuit in front of or behind the coolant pump.

DE 199 01 123 A1 has disclosed a controllable coolant pump with an open impeller wheel. A slide which engages over the vanes of the impeller wheel and therefore influences the effective vane width can be set in an infinitely variable axially movable manner via an adjusting device. U.S. Pat. No. 1,813,747 A discloses a radial pump, in which the delivery volume can be controlled by means of a slide which is arranged on the impeller wheel and can be displaced in the axial direction. The slide is controlled between an open position and a closed position by rotation of a thread-like guide.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a seal for a controllable coolant pump, which seal ensures that no volumetric flow is conveyed when the pump is closed.

Broadly, the invention relates to a coolant pump which has a pump housing, in which a pump shaft that is mounted by roller bearings and is preferably configured as a hollow shaft connects a drive wheel to an impeller wheel. In the operating state of the coolant pump, coolant, in particular cooling water, is sucked in via a suction space by the rotating impeller wheel and is conveyed via the vanes or blades of the impeller wheel into an annular channel of the pump housing. The impeller wheel is assigned on the suction space side a guide plate, which can be displaced axially via an actuator, for directly influencing the delivery volume of the coolant pump.

According to the invention, an elastic sealing element seals a functionally required annular gap between the impeller wheel and the guide plate.

As a result of the axial displacement of the guide plate with respect to the impeller wheel for the variable setting of the volumetric flow of the coolant pump, an annular gap is formed between the circumference of the impeller wheel and of the guide plate and between the vanes of the impeller wheel and corresponding cutouts in the guide plate. As a result of the arrangement according to the invention of a highly elastic sealing element in the largest diameter region of the annular gap between the impeller wheel and the guide plate, a sealing action is produced, via which both components are sealed effectively with respect to one another. This sealing action is configured in such a way that an effective sealing action is ensured in all operating states of the coolant pump, independently of the pressure differences which are produced in the process between the impeller wheel front side and the impeller wheel rear side. Here, the sealing element according to the invention likewise suppresses a flow of the coolant through the functionally required gaps between the vanes of the impeller wheel and the vane cutouts in the guide plate.

Not only a reduction in the volumetric flow, but also a desired zero delivery of the coolant pump in the closed state of the guide plate can advantageously be realized by the concept according to the invention in the case of a closed pump. A disadvantageous circulation within the internal combustion engine of the coolant which is not yet operationally warm is therefore suppressed. The cold running phase which is therefore shortened and the more rapid reaching of the operating temperature reduce the time period for heating the passenger compartment, reduce the friction and, as a result, save energy.

It is provided according to one preferred refinement of the invention that a circumferential, radially oriented annular groove is made in an outer contour of the impeller wheel. This annular groove is intended to receive the sealing element which is supported sealingly on an axially oriented, cylindrical section of the guide plate, which cylindrical section covers the outer contour of the impeller wheel. In order to ensure an effective sealing action in all positions of the guide plate, the cylindrical section of the guide plate extends over a length which exceeds a maximum actuating travel of the guide plate.

A seal which comprises two sealing lips which are spread in opposite directions and are connected via a seal hack is suitable, in particular, for the sealing element according to the invention. In the installed state, the seal is fixed via the seal back in the smallest groove of the impeller wheel, sealing lips being supported sealingly in a prestressed manner on an inner side of the cylindrical section of the guide plate. A spreading element which is inserted between the sealing lips is provided according to the invention as a measure to optimize the sealing quality of this seal. The sealing lips are constantly oriented in an optimum position via the spreading element, independently of the actuating movement of the diffuser.

According to the invention, a diagonally slotted sealing element can be used for sealing the annular gap, as a measure for simple mounting and for avoiding an impermissible expansion of the sealing element. The ends of the sealing element are preferably connected in the region of the separation point by means of an annular lock.

As an alternative to a sealing element which includes sealing lips, other sealing elements can also be used according to the invention such as an O-ring or a quad ring. Furthermore, according to the invention, a reinforced sealing element can be used in a deviation from a single piece construction, in which reinforced sealing element, for example, the reinforcement is introduced in a seal back in order to stiffen the sealing element.

A further refinement of the invention provides that, in a largest circumferential region, the cover disk includes a receptacle for a seal. A gap size between the cover disk and the guide plate can therefore be sealed effectively in an end position of the guide plate, in the case of a closed coolant pump.

The sealing element is preferably configured as a multiple component injection molded part. A highly elastic, wear resistant plastic such as PEEK is suitable, in particular, as material for the sealing element.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantageous further features of the invention result from the following description, in which one exemplary embodiment of the invention is shown.

FIG. 1 shows a detail of a coolant pump with the sealing element according to the invention; and

FIG. 2 shows the details of the sealing element according to FIG. 1 in an enlarged illustration.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a detail of a controllable coolant pump 1, comprising a pump housing 2, in which a hollow shaft 3 is mounted which is connected in a rotationally rigid manner to an impeller wheel 4 and on the other side encloses a drive wheel which is not shown in FIG. 1. In the operating state of the coolant pump 1 when the impeller wheel 4 is rotating, the coolant flows axially via a suction space 5 to the impeller wheel 4 and is guided radially via the vanes 6 into an annular channel 7. Here, a cover disk 8 which rotates jointly with the impeller wheel 4 forms a transition region to the suction space 5. In order to influence the delivery volume of the coolant pump 1, the impeller wheel 4 is assigned an axially displaceable guide plate 9 which is fixed on a push rod 10 which is guided in the hollow shaft 3. At the end which faces away from the impeller wheel 4, the push rod 10 is connected to an adjusting unit (not depicted in FIG. 1), via which the guide plate 9 can be set between two end positions and in any desired intermediate positions. According to FIG. 1, the guide plate 9 is supported in an end position directly on the impeller wheel 4, as a result of which the greatest opening and therefore a maximum delivery volume or a maximum volumetric flow of the coolant pump 1 are set.

In order to achieve a desired zero delivery of the coolant pump 1, the guide plate 9 is adjusted via the adjusting unit until it is supported on the cover disk 8. In this end position, the guide plate 9 is supported sealingly on a seal 11 which is inserted in an outside receptacle 12 of the cover disk 8. Here, the seal 11 which is arranged in a largest circumferential region of the cover disk 8 and is configured as an elastic seal is supported directly on the end side on the guide plate 9. In addition, the coolant pump 1 comprises an elastic sealing element 13 which, inserted in an annular groove 14 of the impeller wheel 4, seals an annular gap 15 which is produced with respect to the diffuser 9. To this end, the diffuser 9 forms an axially oriented, cylindrical section 16 which engages over an outer contour 17 of the guide plate 9, a length S₁ of the cylindrical section 16 exceeding a maximum adjusting movement S₂ of the diffuser 9. As a result of the installation position of the sealing element 13, at the same time a coolant flow between a front side and a rear side of the impeller wheel 4 is suppressed, which coolant flow can be triggered, in particular, by an entry of coolant via opening gaps 18 between the vane 6 and openings 19 of the diffuser 9.

An enlarged illustration in FIG. 2 clarifies the construction and the installation position of the sealing element 13 which comprises two separate, spread sealing lips 20, 21 which are connected via a seal back 22. The sealing element 13 which is inserted positively and nonpositively into the annular groove 15 via the seal back 22 makes an effective sealing action of the annular gap 15 in both adjusting directions of the guide plate 9 possible, as a result of the sealing lips 20, 21 which are spread in opposite directions. In order to assist the spreading, it is possible to additionally introduce a spreading element 23 between the sealing lips 20, 21. The dash-dotted line between the impeller wheel 4 and the guide plate 9 illustrates a flow of the coolant that enters into the annular gap 15 via the opening gap 18 which is formed between the opening 19 and the vane 6, the sealing element 13 suppressing this coolant flow effectively.

LIST OF REFERENCE NUMERALS

-   1 Coolant Pump -   2 Pump Housing -   3 Hollow Shaft -   4 Impeller Wheel -   5 Suction Space -   6 Vane -   7 Annular Channel -   8 Cover Disk -   9 Guide Plate -   10 Push Rod -   11 Seal -   12 Receptacle -   13 Sealing Element -   14 Annular Groove -   15 Annular Gap -   16 Section -   17 Outer Contour -   18 Opening Gap -   19 Opening -   21 Sealing Lip -   22 Sealing Lip -   22 Seal Back -   23 Spreading Element 

1-9. (canceled)
 10. A controllable coolant pump comprising: a pump housing having an annular channel; an impeller wheel, which is arranged within the pump housing, having a guide plate, which can be displaced axially by means of an actuator, in an operating state, a rotation of the impeller wheel sucks in a coolant via a suction space and conveys the coolant into the annular channel of the pump housing, and the guide plate can influence a volume of the coolant that can be delivered; a pump shaft, which is a hollow shaft, arranged within the pump housing and connects a drive wheel to the impeller wheel; and an elastic sealing element sealing an annular gap between the impeller wheel and the guide plate in all operating states of the coolant pump.
 11. The controllable coolant pump according to claim 10, wherein the impeller wheel has an outer contour with a circumferential radially oriented annular groove formed in the outer contour, and wherein the guide plate has an axially orientated, cylindrical section and the annular groove formed in the outer contour of the impeller wheel receives the sealing element, which is supported sealingly on the cylindrical section of the guide plate.
 12. The controllable coolant pump according to claim 11, wherein the cylindrical section of the guide plate has a length that exceeds a maximum actuating travel of the guide plate.
 13. The controllable coolant pump according to claim 10, wherein the sealing element has a seal hack, which is inserted in the annular groove of the impeller wheel and two sealing lips, which are connected by the seal back in order to seal the annular gap.
 14. The controllable coolant pump according to claim 13, further comprising a spreading element inserted between the sealing lips of the sealing element.
 15. The controllable coolant pump according to claim 13, wherein the sealing element is a diagonally slotted sealing element for sealing the annular gap between the impeller wheel and the guide plate.
 16. The controllable coolant pump according to claim 13, wherein the seal back is reinforced for stiffening the sealing element.
 17. The controllable coolant pump according to claim 10, wherein the cover disk has a receptacle for a seal in a largest circumferential region, which seals a gap size between the cover disk and the guide plate in an end position of the guide plate.
 18. The controllable coolant pump according to claim 17, wherein the seal and the sealing element are made of plastic.
 19. The controllable coolant pump according to claim 18, wherein the plastic is PEEK. 